WBCS.LIVE practice question

If x + (1 ÷ x) = 5, what is the exact value of x³ + (1 ÷ x³)?

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. 125
  2. 120
  3. 115
  4. 110

Correct answer and explanation

Correct answer: 110

Explanation: ✅ Correct Answer: D) 110 📚 Explanation: This relies on a standard algebraic identity. If a given variable x + (1 ÷ x) = a, then the value of x³ + (1 ÷ x³) is always equal to a³ - 3a. In this problem, the value of 'a' is 5. Substituting 5 into the formula gives 5³ - 3(5), which is 125 - 15. The final answer perfectly simplifies to 110.